Redescription of Dexiotricha colpidiopsis (Kahl, 1926) Jankowski, 1964 (Ciliophora, Oligohymenophorea) from a Hot Spring in Iceland with Identification Key for Dexiotricha species

摘要

We isolated an encysted ciliate from a geothermal field in Iceland. The morphological features of thisisolate fit the descriptions of Dexiotricha colpidiopsis (Kahl, 1926) Jankowski, 1964 very well. Thesecomprise body shape and size in vivo, the number of somatic kineties, and the positions ofmacronucleus and contractile vacuole. Using state-of-the-art taxonomic methods, the species isredescribed, including phylogenetic analyses of the small subunit ribosomal RNA (SSU rRNA) gene asmolecular marker. In the phylogenetic analyses, D. colpidiopsis clusters with the three available SSUrRNA gene sequences of congeners, suggesting a monophyly of the genus Dexiotricha. Its closestrelative in phylogenetic analyses is D. elliptica, which also shows a high morphological similarity. Thisis the first record of a Dexiotricha species from a hot spring, indicating a wide temperature toleranceof this species at least in the encysted state. The new findings on D. colpidiopsis are included in abriefly revision of the scuticociliate genus Dexiotricha and an identification key to the species.